From 57050567c4f959223316be97a9a52b8bccf48ae3 Mon Sep 17 00:00:00 2001
From: kieran <kieran@harkin.me>
Date: Thu, 27 Feb 2025 16:16:37 +0000
Subject: [PATCH] fix: invalid range for size

---
 src/routes/mod.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/routes/mod.rs b/src/routes/mod.rs
index 1e5a755..9704d95 100644
--- a/src/routes/mod.rs
+++ b/src/routes/mod.rs
@@ -138,7 +138,7 @@ impl RangeBody {
     pub fn get_range(file_size: u64, header: &SyntacticallyCorrectRange) -> Range<u64> {
         let range_start = match header.start {
             StartPosition::Index(i) => i,
-            StartPosition::FromLast(i) => file_size - i,
+            StartPosition::FromLast(i) => file_size.saturating_sub(i),
         };
         let range_end = match header.end {
             EndPosition::Index(i) => i,
@@ -514,6 +514,11 @@ mod tests {
         let r = RangeBody::get_range(size, req.ranges.first().unwrap());
         assert_eq!(r.start, 16482459);
         assert_eq!(r.end, 16482468);
+
+        let req = parse_range_header("bytes=-16482470")?;
+        let r = RangeBody::get_range(size, req.ranges.first().unwrap());
+        assert_eq!(r.start, 0);
+        assert_eq!(r.end, 16482468);
         Ok(())
     }
 }
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